METACHROMASIA (metachromasia; grech, meta-through, by means of + chroma color, coloring) — property of cells and fabrics to be painted in the presence of hromotropny substances in the tone different from color of dye. In biol, objects such hromotropny substances more often are mucopolysaccharides (see) or glikozaminoglikana (hyaluronic and chondroitinsulphuric to - you, heparin, keratosulfate, etc.), and also nucleic acids (see). For M.'s identification are used toluidine blue (see), azur And, methylene blue (see), thionine (see), cresylic blue (see. Brilliantkrezilblau ), the main fuchsin (see), etc.; the dyes of tiazinovy group causing discoloration of coloring from blue through violet to red are more often applied. In relation to toluidine blue allocate the beta metachromasia (violet coloring) caused by high concentration of weak acid groups and the gamma metachromasia (red coloring) connected with presence of ethers a chamois to - you.
The mechanism M. is found out insufficiently. Many researchers consider that M. is caused by polymerization of dye, to-ruyu stimulate hromotropny substances.
Special methods of identification of glikozaminoglikan by means of alcian blue across Stidmen and dializovanny iron according to Hale, definitions of different types of glikozaminoglikan by means of dializovanny iron are based on M.'s phenomenon, CHIC reaction (see) and Ritter's reactions — Olesona. M use for identification of mucoid and fibrinoid swelling, fibrinoid of connecting fabric at collagenic diseases, hypoxemic states, etc. Metachromatic coloring methylene blue is one of the most sensitive and reliable methods of identification of amyloid. Ability nucleinic to - t to M. is used during the studying of lymphoid system in the conditions of an antigen challenge, allergic reactions, etc.
Bibliography: Lille R. D. Patogistologicheskaya of the technician and a practical histochemistry, the lane with English, M., 1969; Pearce E. A histochemistry, the lane with English, M., 1962; Handbuch der Histochemie, hrsg. v. W. Grau-mann u. K. Neumann, Bd 1, T. 1-2, Stuttgart, 1958 — 1966; Kiszely Gy. u. P 6 s a 1 a k at Z. Mikrotechnische und histochemische Untersuchungsmethoden, Budapest, 1964.
B. B. Serov.